Field of the Invention
The present invention relates to wireless communication and, most particularly, to a method for transmitting data in a wireless LAN and a device using the same.
Related Art
Wi-Fi refers to a WLAN (Wireless local area network) technology that allows a wireless device to be connected to the Internet in a 2.4 GHz, 5 GHz, or 60 GHz frequency band. WLAN is based on an IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard (or specification).
The IEEE 802.11n specification supports multi-antenna and provides a maximum data rate of 600 Mbit/s. A system that supports IEEE 802.11n is referred to as a HT (High Throughput) system.
The IEEE 802.11ac specification mostly operates in a 5 GHz band and provides a data rate of 1 Gbit/s or more. IEEE 802.11ac supports DL MU-MIMO (downlink multi-user multiple input multiple output). And, a system supporting IEEE 802.11ac is referred to as a VHT (Very High Throughput) system.
IEEE 802.11ax is being developed as a next generation WLAN in order to prepare for a higher data rate and a higher user load. The scope of the IEEE 802.11ax may include 1) an enhancement of the 802.11 PHY (physical) layer and the MAC (medium access control) layer, 2) an enhancement in a spectrum efficiency and area throughput, and 3) an enhancement in the system performance in an environment having a source of interference existing therein, a dense heterogeneous network environment, an environment having a high user load existing therein, and so on.
The legacy IEEE 802.11 specification (or standard) supports OFDM (orthogonal frequency division multiplexing) and uses only one FFT (fast Fourier transform) size in the same bandwidth. However, the next generation WLAN considers supporting OFDMA (orthogonal frequency division multiple access), wherein multiple user access is available, and using a larger FFT size.